From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kay Sievers Date: Thu, 09 Dec 2004 17:32:53 +0000 Subject: Re: udev / hotplug / hald / dbus Message-Id: <1102613573.6848.12.camel@localhost.localdomain> List-Id: References: <20041209171538.GB17970@fmp.com> In-Reply-To: <20041209171538.GB17970@fmp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org On Thu, 2004-12-09 at 11:15 -0600, Lindsay Haisley wrote: > I'd like to know how the udev / hotplug mechanism works with the hald / dbus > hardware abstraction/detection/notification system which is apparently > becoming the defacto standard in Gnome. It looks as if there may be some > duplication of effort here, at some level. I had to disable my auto device > mounts in /etc/dev.d after I recently updated gnome and had to install hald > and the dbus-daemon to get features in Gnome to work, such as auto-detection > of CD-RW disks. It looks as if auto-detection and mounting of USB storage > devices is also supported and enabled by hald / dbus, at least in Gnome. > > I'm certainly no expert in these matters, and the answer may be obvioius to > anyone with more experience at a hardware level, but it looks as if there > may be some functional overlap and possibly potential for conflict with > these two systems. The kernel creates/removes devices. The information about that is exposed in sysfs. Changes in sysfs are notified from the kernel to userspace by executing /sbin/hotplug. udev is a devfs implementation. It uses the events and sysfs to maintain the /dev directory. On node creation/removal the dev.d/ scripts are called. HAL also listens to the hotplug events and gets the name of the created node from udev. HAL is a hardware abstraction that keeps it's own device list inside a daemon, based on the events hotplug sends. HAL's string based interface is easy to use from any application, cause the D-BUS IPC can inform any application interested in device changes. An application can subscribe to certain device events or a whole class of device events. One example of a HAL subscriber is the gnome-volume-manager, which can mount your devices automatically. I don't see any overlap, besides your own dev.d/ script. :) Kay ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://productguide.itmanagersjournal.com/ _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel